Background: Sanguinarine, a benzophenanthridine alkaloid, is extracted from the rhizomes of Sanguinaria canadensis and other poppy species (Fumaria). Although its antitumor activity is not fully understood, sanguinarine has demonstrated various biological effects, including antioxidant, antimicrobial, and anti-inflammatory properties. This work hypothesizes that sanguinarine's novel anti-angiogenic mechanism may enhance the efficacy of anticancer therapy.

Methods: The Cell Counting Kit-8 (CCK-8) assay and colony formation assay were conducted to evaluate the effect of sanguinarine on angiogenesis. Preliminary mechanisms of sanguinarine were investigated through cell cycle and apoptosis assays. A tube formation assay was performed to examine the impact of sanguinarine on angiogenesis in vitro. RT-qPCR and western blot analyses were primarily used to elucidate the underlying mechanisms, which were further validated through a vascular endothelial growth factor (VEGF) recovery experiment. Additionally, an animal xenograft model was employed to assess the effect of sanguinarine on tumor growth and to analyze potential toxicity.

Results: Sanguinarine significantly inhibited the proliferation of rat smooth muscle cells (A7r5) and human microvascular endothelial cells (HMVECs) and increased the cell population in the G2/M phase (p < 0.05). Sanguinarine also reduced cell migration capacity and angiogenesis (p < 0.05). These effects were mediated by inhibiting the VEGF signaling pathway, as sanguinarine downregulated VEGF expression at both mRNA and protein levels, with partial recovery observed upon VEGF supplementation in the medium (p < 0.05). Additionally, sanguinarine exposure inhibited phosphorylation activity across multiple kinases downstream of VEGF (p < 0.05). In animal experiments, sanguinarine suppressed tumor growth without significant toxicity (p < 0.05).

Conclusion: Sanguinarine exerts an inhibitory effect on blood vessel cell proliferation, presenting a valuable therapeutic approach in cancer treatment.